Cylinder lock

Abstract: A lock piece is provided in the inner part of a tumbler. Size of a clearance formed between the side of a lock groove engaging portion of the lock piece and the side of a lock groove is determined to be smaller than size of a clearance formed between the side of a lock condition holding portion of the tumbler and the side of a lock groove. When the key is inserted being given a torque in the rotating direction, the lock groove engaging portion is engaged with the side of the lock groove, and the lock condition holding portion of the tumbler is maintained to be separate from the side of the lock groove. Due to the foregoing, the lock condition holding portion is prevented from being caught on the side of the lock groove.

Description: The present invention relates to a cylinder lock comprising a rotor case provided with a lock groove in the inner circumferential portion thereof, a rotor rotatably accommodated in the rotor case, the rotor having a keyhole extending in the axial direction and a tumbler insertion hole extending in the radial direction, at least one tumbler movably inserted into the tumbler insertion hole of the rotor, the tumbler including at least one lock condition holding portion for holding the rotor in a lock condition and at least one lock condition release portion for releasing said rotor. Such a cylinder lock is known from FR-A-1 493 687. Conventionally, in this type cylinder lock, tumblers are movably inserted into a plurality of tumbler insertion holes provided in the rotor, and when a key is not inserted into the keyhole, a lock condition holding portion of each tumbler is engaged with a lock groove in the rotor case, so that the rotor can be maintained in a lock condition. According to the device described above, when the key is inserted into the keyhole, a protruding and cutout portion of the key is engaged with the lock condition release member of the tumbler. In the process of insertion of the key, each tumbler is pushed upward or downward along the protruding and cutout portion of the key. After the completion of key inserting operation, the protruding and cutout portion of the key is engaged with a predetermined lock condition release portion of the tumbler, and the tumbler is moved so that the lock condition holding portion can be released from the lock groove. Next, the key is operated so as to rotate the rotor. In this connection, when an operator inserts the key into the keyhole, he is well aware of the rotational operation of the key to be conducted after the insertion of the key. Therefore, he tends to insert the key into the keyhole while a torque is applied to the key. However, in the conventional construction described above, when the key is inserted into the keyhole while a torque is applied to the key, the tumblers which are pushed upward or downward come into pressure contact with a side of the lock groove. Therefore, even after the key inserting operation has been completed, the tumblers can not be moved due to a frictional force generated between the tumblers and the side of the lock groove. For this reason, there is a possibility that the lock condition holding portion is not disengaged from the lock groove. When the lock condition holding portion is not disengaged from the lock groove, the next rotational operation of the key can not be smoothly performed. SUMMARY OF THE INVENTION The present invention has been achieved in view of the above circumstances. It is an object of the present invention to provide a cylinder lock in which the rotational operation of the key can be smoothly performed even after the key has been inserted into the keyhole while a torque is applied to the key. According to the present invention, this objective is solved for a cylinder lock as indicated above in that said lock condition holding portion is adapted to engage with the lock groove of the rotor case when a key is not inserted into the keyhole, that said lock condition release portion is provided in the tumbler, the lock condition release portion allowing the tumbler to move so as to disengage the lock condition holding portion from the lock groove when the key is inserted into the keyhole with the lock condition release portion being engaged with a protruding and cutout portion of the key, and a lock piece is movably provided in the rotor, the lock piece being located in the inner part of the tumbler, the lock piece including rotor position holding means for holding the rotor in a predetermined portion when the key (4) is not inserted into the keyhole. In that case, it is advantageous when the rotor position holding means includes a lock groove engaging portion engaging with the lock groove of the rotor case. Further, it is possible that a clearance between the side of the lock groove engaging portion of the lock piece and the side of the lock groove is determined to be smaller than a clearance between the side of the lock condition holding portion and the side of the lock groove so as to hold the lock condition holding portion of the tumbler to be separate from the side of the lock groove when the rotor is rotated under a lock condition. According to an advantageous and preferred embodiment, a lock piece moving portion is provided at least at one end of the key and the lock piece, and the lock piece moving portion forcibly moves from the lock groove engaging portion coming into contact with the side of the lock groove so as to disengage the lock groove engaging portion from the lock groove when the key is inserted into the keyhole. According to the above means, when the key is inserted into the keyhole being given a torque, first, the lock groove engaging portion of the lock piece is engaged with a side of the lock groove, and the lock condition holding portion of the tumbler is held under the condition that the lock condition holding portion is separate from the side of the lock groove. Accordingly, the lock condition holding portion of the tumbler is not caught on the side of the lock groove in the process of insertion of the key. Therefore, the lock condition holding portion is smoothly pushed upward or downward along the protruding and cutout portion of the key. After the key insertion operation has been completed, the protruding and cutout portion of the key is engaged with a predetermined lock condition release portion of the tumbler, and the tumbler is moved so that the lock condition holding portion can be disengaged from the lock groove. When the lock piece moving portion provided at least in one of the end of the key and the lock piece is engaged with the opponent, the lock groove engaging portion is forcibly moved so that the lock groove engaging portion gets out of the lock groove. Due to the foregoing, the lock groove engaging portion of the lock piece is disengaged from the lock groove, and the rotational operation of the key can be smoothly performed. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view of an example of the present invention taken on line A - A in Fig. 2; Fig. 2 is a longitudinal sectional view of the overall arrangement of the present invention; Fig. 3 is a front view of the cover of the present invention; Fig. 4 is a sectional view taken on line B - B in Fig. 2; Fig. 5 is a sectional view taken on line C - C in Fig. 2; Fig. 6 is a sectional view taken on line D - D in Fig. 2; and Fig. 7 is a sectional view corresponding to Fig. 2 for explaining the operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the accompanying drawings, an example will be explained as follows in which the present invention is applied to an ignition key unit for use in an automobile. Referring to Fig. 2, a rotor 2 is rotatably accommodated in a cylindrical rotor case 1. A keyhole 2a is provided in this rotor 2 in the axial direction. A front face of the rotor case 1 is covered with a cover 3. The cover 3 is provided with an opening 3a. When a key 4 is inserted into a keyhole 2a through this opening 3a of the cover 3 and the key 4 is rotated to the right, that is, when the key 4 is rotated in the direction shown by arrow A in Fig. 3, a starter of the engine is turned on. In this connection, as illustrated in Fig. 3, the cover 3 is provided with a shutter 3b. Usually, the opening 3a is closed by the shutter 3b. When the key 4 is inserted into the opening 3a, the shutter 3b is pushed and opened by the key 4. In this way, the key 4 is allowed to be inserted. As illustrated in Fig. 2, for example, 7 tumbler insertion holes 2b are provided in the rotor 2 in the radial direction. Sheet-shaped tumblers 5 and 6 are movably inserted into the tumbler insertion holes 2b. As illustrated in Fig. 4, in the former tumbler 5, a spring engaging portion 5a is protruded at an upper side position of the tumbler 5, and a lock condition holding portion 5b is provided at an upper end portion of the tumbler 5. There is provided a lock groove la on an upper side of the inner circumferential portion of the rotor case 1. In the rotor 2, there is provided a cutout portion 2c at a position in the tumbler insertion hole 2b. A spring engaging portion 5a of the tumbler 5 is inserted into the cutout portion 2c of the rotor 2. A compression coil spring 7 is interposed between the spring engaging portion 5a and a lower surface of the cutout portion 2c. Due to the foregoing construction, the tumbler 5 is protruded upward, and the lock condition holding portion 5b is engaged with the lock groove la in the rotor case 1. There is provided a key insertion hole 5c at the center of the tumbler 5. When the key 4 is inserted into the key insertion hole 5c, a protruding and cutout portion 4a formed in a lower edge portion of the key 4 is engaged with a lower surface of the insertion hole 5c, and each tumbler 5 is lowered, resisting a force of the compression coil spring 7 (shown in Fig. 7). Due to the foregoing, the lock condition holding portion 5b of each tumbler 5 gets out of the lock groove la of the rotor case 1. As described above, the lower surface of the key insertion hole 5c functions as the lock condition release portion 5d. Fig. 5 shows a tumbler 6. A different point between the tumblers 5 and 6 is that a spring engaging portion 6a is provided at a lower position in the side, and a lock condition holding portion 6b is provided at a lower end portion. Concerning the rotor case 1, the lock groove 1b is provided at a lower position of the inner circumferential portion. In the rotor 2, there is provided a cutout portion 2d into which the spring engaging portion 6a is inserted. The tumbler 6 is protruded downward by the compression coil spring 7 interposed between the upper surface of the cutout portion 2d and the spring engaging portion 6a. Therefore, the lock condition holding portion 6b is engaged with the lock groove 1b. There is provided a keyhole 6c at a center of the tumbler 6. In this case, an upper surface of the keyhole 6c functions as the lock condition release portion 6d. In this case, when the key 4 is inserted into the keyhole 6c, the protruding and cutout portion 4a formed at an upper edge of the key 4 is engaged with the lock condition release portion 6d. Therefore, each tumbler 6 is pushed upward, resisting a spring force of the compression coil spring 7 (shown in Fig. 7). Due to the foregoing, the lock condition holding portion 6b of each tumbler 6 gets out of the lock groove 1b of the rotor case 1. As illustrated in Fig. 2, a lock piece insertion hole 2e is formed at an inner part of 7 tumbler insertion holes 2b in the rotor 2. A thick lock piece 8 is movably inserted into this lock piece insertion hole 2e. As shown by the solid line in Fig. 1, this lock piece 8 includes a spring engaging portion 8a located at an upper side of the lock piece 8, and a lock groove engaging portion 8b located at an upper end portion of the lock piece 8. A cutout portion 2f is formed in the lock piece insertion hole 2e of the rotor 2. The spring engaging portion 8a of the lock piece 8 is inserted into the cutout portion 2f. The compression coil spring 7 is interposed between a lower surface of the cutout portion 2f and the spring engaging section 8a. Due to the foregoing construction, the lock piece 8 is protruded upward, and the lock groove engaging portion 8b is engaged with the lock groove la of the rotor case 1. Width W1 of the lock groove engaging portion 8b of the lock piece 8 is determined to be larger than width W2 of the lock condition holding portions 5b, 6b of the tumblers 5, 6. In Fig. 1, only a relation between the lock groove engaging portion 8b and the lock condition holding portion 6b is illustrated. Due to the foregoing, size D1 of a clearance formed between a right side of the lock groove engaging portion 8b and a side of the lock groove la correspondingly to the rotational direction of the key 4 (the direction indicated by arrow A), is determined to be smaller than size D2 of a clearance formed between the lock condition holding portion 6b (5b) and the lock groove 1b (1a). Consequently, when the rotor 2 is rotated under a locked condition, that is, when the rotor 2 is rotated under the condition that the lock condition holding portions 5b, 6b of the tumblers 5, 6 are engaged with the lock grooves 1a, 1b of the rotor case 1, the lock groove engaging portion 8b of the lock piece 8 is engaged with the right side of the lock groove 1a, and the left side of the lock condition holding portion 6b is separate from the left side of the lock groove 1b, and also the right side of the lock condition holding portion 5b is separate from the right side of the lock groove 1a. In this connection, the side 8e of a portion (shown by the solid line in the drawing) of the lock groove la with which the lock groove engaging portion 8b of the lock piece 8 is engaged is extended to a direction opposite to the rotational direction as compared with a portion (shown by the two-dotted chain line in the drawing) with which the lock condition holding portion 5b of the tumbler 5 is engaged. Further, the side 8f of a portion (shown by the solid line in the drawing) opposed to a portion of the lock groove 1b with which the lock groove engaging portion 8b is engaged is extended to a direction opposite to the rotational direction as compared with a portion (shown by the two-dotted chain line in the drawing) with which the lock condition holding portion 6b of the tumbler 6 is engaged. A key insertion hole 8c into which the key 4 is inserted is formed in the lock piece 8. In this case, when a lower surface of the key insertion hole 8c is formed into a slope as illustrated in Fig. 2, a diameter of the key insertion hole 8c is gradually reduced as it advances from the insertion start end to the insertion completion end. Also, a lower surface of the fore end of the key 4 is formed into a slope. Therefore, the lower surface of the fore end of the key 4 and the lower surface of the key insertion hole 8c function as the lock piece moving portions 4b, 8d. Consequently, when the key 4 is inserted into the key insertion hole 8c, the lock piece moving portion 8d of the lock piece 8 is pushed by the lock piece moving portion 4b of the key 4, so that the lock piece 8 is pushed downward. As illustrated in Fig. 6, a protrusion 1c is formed in the rotor case 1. A moderation member 9 is movably accommodated in this protrusion 1c. A compression coil spring 10 is interposed between this moderation member 9 and a ceiling surface of the protrusion 1c. Also, a key way 2g, the section of which is arcuate, is formed in the rotor 2. The moderation member 9 is engaged with the key way 2g by the action of the compression coil spring 10. Due to the foregoing construction, the rotor 2 is positioned at a position defined as "Lock Position" shown in the drawing. In this connection, as illustrated in Fig. 2, a stopper 9a is provided in the moderation member 9. Accordingly, a protruding position at which the moderation member 9 is protruded is regulated when the stopper 9a comes into contact with the engaging portion 1d of the rotor case 1. Next, the operation of the construction described above will be explained below. First, in Fig. 2, the key 4 is inserted into the opening 3a of the cover 3. Then the shutter 3b is opened being pushed by the key 4, and the key 4 is inserted into the keyhole 2a of the rotor 2. When the protruding and cutout portion 4a of the key 4 is engaged with the lock condition release portions 5d, 6d, the tumblers 5, 6 are pushed upward or downward in the process of insertion of the key 4. When the key 4 is completely inserted, the protruding and cutout portion 4a of the key 4 is engaged with the lock condition release portion 5d of the predetermined tumbler 5 and the lock condition release portion 6d of the predetermined tumbler 6. As a result, the tumbler 5 is moved downward, and the tumbler 6 is moved upward. Due to the foregoing operation, as illustrated in Fig. 7, the lock condition holding portion 5b of the tumbler 5 gets out of the lock groove 1a, and the lock condition holding portion 6b of the tumbler 6 gets out of the lock groove 1b. At the same time, the lock piece moving portion 4b of the key 4 is engaged with the lock piece moving portion 8d of the lock piece 8, and the lock piece moving portion 4b of the key 4 pushes the lock piece moving portion 8d of the lock piece 8. Due to the foregoing, the lock piece 8 is forcibly lowered. Accordingly, the lock groove engaging portion 8b of the lock piece 8 gets out of the lock groove 1a, so that the rotor 2 is allowed to rotate. Consequently, the key 4 is operated so that it is rotated to the right. In this connection, when thus rotated key 4 is returned to the left, the key way 2g of the rotor 2 is engaged with the moderation member 9, and the rotor 2 is positioned at a position defined as "Lock Position". In this connection, this cylinder lock is constructed in such a manner that the key 4 is rotated to the right from "Lock Position" to "ACC position" and the like. Accordingly, the operator sometimes inserts the key 4 into the keyhole while a torque is applied to the key so that the key 4 is rotated to the right. Then, in Fig. 1, the lock groove engaging portion 8b of the lock piece 8 is engaged with the right side of the lock groove 1a. In this case, size D1 of the clearance between the side of the lock groove engaging portion 8b and the side of the lock groove la is determined to be smaller than size D2 of the clearance between the right side of the lock condition holding portion 5b and the right side of the lock groove 1a, and also size D1 is determined to be smaller than size D2 of the clearance between the left side of the lock condition holding portion 6b and the left side of the lock groove 1b. Therefore, the lock condition holding portions 5b and 6b are maintained to be separate from the concerned sides. Consequently, the tumblers 5, 6 are pushed upward or downward along the protruding and cutout portion 4a of the key 4 while the lock condition holding portions 5b, 6b are not caught on the sides of the lock grooves 1a, 1b in the process of insertion of the key 4. After the inserting operation of the key 4 has been completed, the protruding and cutout portion 4a of the key 4 is engaged with the predetermined lock condition release portions 5d, 6d, and the lock condition release portion 5b is released from the lock groove 1a, and also the lock condition holding portion 6b is released from the lock groove 1b. Therefore, the tumblers 5, 6 are smoothly moved. At the same time, as illustrated in Fig. 7, the lock piece moving portion 4b of the key 4 is engaged with the lock piece moving portion 8d of the lock piece 8, and the lock piece 8 is forcibly lowered. Due to the foregoing, the lock groove engaging portion 8b of the lock piece 8 gets out of the lock groove 1a, and the lock groove engaging portion 8b is released from the lock groove 1a. Accordingly, at a point of time when the insertion of the key 4 has been completed, the lock condition of the rotor 2 is quickly released. As a result, the next rotational operation of the key 4 can be smoothly performed. In this connection, in the above example, the slope-shaped lock piece moving portions 8d, 4b are provided at the end of the lock piece 8 and also the end of the key 4. However, a lower surface of the end of the key 4 may be formed to be flat so that only the slope of the lock piece 8 is used as the lock piece moving portion 8d, or alternatively a lower surface of the key insertion hole 8c of the lock piece 8 may be formed to be flat so that only the slope of the key 4 is used as the lock piece moving portion 4b. In the above example, the rotor 2 is rotated by the key 4 in which the protruding and cutout portion 4a is provided outside on both the upper and lower surfaces. However, it should be noted that the present invention is not limited to this type of key, and the rotor 2 may be rotated by the key 4 in which the protruding and cutout portion 4a is provided inside. In the above example, the present invention is applied to the ignition key unit, however, the present invention is not limited to the specific example. For example, the present invention may be applied to a key to the door of an automobile. As can be seen from the above explanation, according to the cylinder lock of the present invention, when a key is inserted into a keyhole while a torque is applied to the key, the lock groove engaging portion of the lock piece is engaged with a side of the lock groove, and then the lock condition holding portion of the tumbler is maintained to be separate from the side. Therefore, the lock condition holding portion of the tumbler is prevented from being caught in the lock groove. As a result, even if the key is inserted into the keyhole while a torque is applied to it, the rotational operation of the key can be carried out without causing any problems.

Claims: A cylinder lock comprising: a rotor case (1) provided with a lock groove (1a) in the inner circumferential portion thereof; a rotor (2) rotatably accommodated in the rotor case (1), the rotor (2) having a keyhole (2a) extending in the axial direction and a tumbler insertion hole (2b) extending in the radial direction; at least one tumbler (5,6) movably inserted into the tumbler insertion hole (2b) of the rotor (2), the tumbler (5,6) including: at least one lock condition holding portion (5b,6b) for holding the rotor (2) in a lock condition and at least one lock condition release portion (5d,6d) for releasing said rotor (2), characterized in that said lock condition holding portion (5b,6b) is adapted to engage with the lock groove (1a) of the rotor case (1) when a key (4) is not inserted into the keyhole (2a); that said lock condition release portion (5d,6d) is provided in the tumbler (5,6), the lock condition release portion (5d,6d) allowing the tumbler (5,6) to move so as to disengage the lock condition holding portion (5b,6b) from the lock groove (1a) when the key (4) is inserted into the keyhole (2a) with the lock condition release portion (5d,6d) being engaged with a protruding and cutout portion (4a) of the key (4); and a lock piece (8) is movably provided in the rotor (2), the lock piece (8) being located in the inner part of the tumbler (5,6), the lock piece (8) including: rotor position holding means (29,9,10) for holding the rotor (2) in a predetermined portion when the key (4) is not inserted into the keyhole (2a). A cylinder lock as claimed in claim 1, wherein the rotor position holding means (2g,9,10) includes a lock groove engaging portion (8b) engaging with the lock groove (1a) of the rotor case (1). A cylinder lock as claimed in claim 2, wherein a clearance (D1) between the side of the lock groove engaging portion (8b) of the lock piece (8) and the side of the lock groove (1a) is determined to be smaller than a clearance (D2) between the side of the lock condition holding portion (5b) and the side of the lock groove (1a) so as to hold the lock condition holding portion (5b) of the tumbler (5,6) to be separate from the side of the lock groove (1a) when the rotor (2) is rotated under a lock condition. A cylinder lock as claimed in claim 1, wherein a lock piece moving portion (8d) is provided at least at one end of the key (4) and the lock piece (8), and the lock piece moving portion (8d) forcibly moves from the lock groove engaging portion (8b) coming into contact with the side of the lock groove (1a) so as to disengage the lock groove engaging portion (8b) from the lock groove (1a) when the key (4) is inserted into the keyhole (2a).

Inventors: YASUHARA NOBUYOSHI, YASUHARA, NOBUYOSHI
Applicants: TOKAI RIKA CO LTD, KABUSHIKI KAISHA TOKAI RIKA DENKI SEISAKUSHO
Application year: 1994
Main classification: E05B29
IPC codes: E05B29